In ovariectomized dexamethasone pretreated estradiol benzoate (EB) primed females with multiple sets of intracerebral double walled cannulas we plan to test the effects of PGE2 on the induction of sexual recepticity, hyperthermia, LH secretion and open field activity. We will also test the effects of the PG biosynthesis inhibitor indomethacin. In similarly prepared rats we will test the effects of GABA and picrotoxin; LHRH and anti-LHRH; and in females receiving sc progesterone we will test the effects of intracerebral application of the anti-progestin R2323. In testosterone treated castrate male rats we will test the effects of intracerebral application of the anti-estrogen CN-69, 725-27 on sexual behavior and LH and FSH secretion. In similar studies we will test the effects of intracerebral application of the 5-alpha reductase inhibitor 4-androsten-3-one, 17 beta carboxylic acid on LH and FSH secretion in testosterone and dihydrotestosterone treated castrate male rats. We plan to complete several studies on the effects of ovarian hormones on GABA uptake by hypothalamic synaptosomes and on hypothalamic and limbic GAD activity. We plan several studies aimed at characterizing the physical an chemical properties of cytosol and nuclear macromolecular receptors for progesterone and dihydrotestosterone in a variety of brain regions. BIBLIOGRAPHIC REFERENCES: LUTTGE, W.G. and NR. Hall (1976) Interactions of progesterone and dihydroprogesterone with dihydrotestosterone on estrogen activated sexual receptivity in female mice. Horm. Behav. (in press). LUTTGE, W.G., H.E. Gray and J.R. Hughes (1976) Reaional and subcellular localization of H3 estradiol in brain and pituitary of female mice: effects of unlabeled estradiol benzoate and various anti-hormones. Brain Research (in press).